A wind turbine transforms wind energy into electrical energy.
The wind energy causes a rotation of the rotor of the wind turbine. The rotor of the wind turbine comprises a hub and at least one rotor blade mounted to the hub. The hub is connected rotatable to the nacelle. The nacelle comprises an electrical generator. The rotation of the hub is transferred to the generator and the generator transfers the rotational energy into electrical energy.
The loads of the wind acting on the rotor are transferred over one or more bearings to a load-carrying structure. The load-carrying structure is a part of the nacelle and connects the nacelle to the tower of the wind turbine. The loads and the weight of the components of the rotor and the nacelle are transferred to the tower.
The load-carrying structure is connected to a tower in a way that the nacelle may be rotated on the tower. A yaw system rotates the nacelle on the tower in a way that the rotor of the wind turbine faces the direction of the wind.
A wind turbine comprises different systems and components that are necessary for the operation of the wind turbine like a control system or a cooling system. The systems and components are connected by electrical connections, hydraulic connections or fluid tight pipes for example for the cooling system. Most of the systems and components are located in the nacelle of the wind turbine.
Some of the systems and components, like the electrical system, are mounted on a support structure. The support structure is connected to the load-carrying structure of the nacelle.
The nacelle of a wind turbine proves to be a critical part in respect of the operational reliability and life-time of the wind turbine. The nacelles of wind turbines are produced in an in-line-production in the factory to achieve a cost effective production and a high quality. The nacelle is then shipped to the erection site of the wind turbine.
In recent year the effective electrical power generated with a single wind turbine continuously increased. The components of the wind turbine, like the blades, the hub, the nacelle and segments of the tower also increased in size and weight.
The size and weight of the single parts of the wind turbine are limited due to the regulations for the transport of the parts on public roads. This is also the case for the nacelle of the wind turbine.
The transport on public roads requires a certain maximum size of the components and specialized transport vehicles. In addition a special heavy-load transport requires a long period for planning and to get the required permission from the authorities.